1. Field of the Invention
This invention generally relates to the field of stepper motors and more particularly to an apparatus for and method of, electronic stepper motor control when power is first applied to a stepper motor.
2. Background of the Invention
When power is initially applied to prior art stepper motors and associated drives there is a high probability that its rotor will snap, rather than move smoothly, into a detent position defined by its phase coils and or a magnetic path. The reason is that there are typically 4 natural detent (rest) states for each 360 electrical degrees (4 steps) of motor driver output signal. If the state of a motor driver signal at power up does not match the initial rest state of the rotor, the rotor will snap to the position called for by the state of the motor driver as the motor coils are energized.
This characteristic of prior art stepper motors and associated motor drivers is undesirable because it can lead to noisy clunks upon initial power up and/or initial motor engagement, giving the final machine a less than professional presence; lead to undesirable initial current surges; result in a number of steps before stepper position and motor drive are “in phase” and/or increase the tendency towards oscillations during initial power up state.